JPH03214463A - Magnetic disk system - Google Patents

Abstract

PURPOSE:To shorten rotation latency time in the readout of a disk by performing the synchronous driving of two sets of disk devices at the same speed so that the phase difference of rotation can be set at 1/2 the rotational cycle of the disk, and writing data on the same sector of the same track. CONSTITUTION:The delay time of a delay circuit 7 is set at 1/2 of the rotational cycle T, and the output signal of the circuit 7 is set so as to be delayed by T/2 than the index pulse signal 6 of the disk device A5a than is an input signal to the circuit 7. The disk devices 5a, 5b are rotated at the same speed, and the output signal 8 of the delay circuit 7 is sent to the disk device 5b, and rotating speed is controlled synchronizing with the signal 8 by the rotational synchronizing function of the device 5b, and the synchronous driving is performed so as to set the phase difference of the devices 5a, 5b at T/2. The same data is written on the same sectors of the same tracks of the devices 5a, 5b. Since the phase difference of T/2 exists between the devices 5a, 5b, mean rotation latency time in the readout of the disk goes to T/4.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a magnetic disk system that performs double writing of the same data on two disk devices, and particularly to a reduction in the waiting time for disk rotation when reading data from the magnetic disk system. It is something.

[Prior Art] In order to prevent the entire system from going down due to failure of a disk device, for example, a conventional magnetic disk system uses two disk devices to write the same data twice. Publication No. 60-144820 “
There are inventions such as those disclosed in "I/O Channel Processing Device".

Figure 6 is a block diagram schematically showing the configuration of such a conventional magnetic disk system that performs double writing of the same data on two disk devices. In the figure, (1) is the system bus, and (2) is the central Processing device (hereinafter referred to as CPU),
(3) is a memory, (4) is a controller, (5a) is a disk device A, and (5b) is a disk device B.

Note that disk device A (5a) and disk device B (5a)
b) assumes that the head arms are located at the same cylinder address.

Next, the operation will be explained. When a data write request is given from the CPU (2) to the controller (4) via the system bus (1), the controller (4) writes the data to the disk device A ( 5a), disk device I3 (5b)
A seek instruction is issued for each of the .

Then, disk device A (5a), disk device B (
The two disk devices 5b) start seek operations almost simultaneously and end their seek operations almost simultaneously. When this seek operation is completed, controller 1/roller (4) waits for the disks of both disk devices (5a>. (5b)) to rotate.
■When the target sector is reached, the same data sent from the memory (3) is transferred to each disk device (5a). (
5b).

Also, when a data read request is given from the CPU (2> to the controller (4) via the system bus (1), the operation is almost the same as in the case of a data write request as described above. The difference from the request is that data is read only from the magnetic disk device that reached the target sector earlier during the rotation wait after the end of the normal seek operation, and the data read operation ends when this data is read. There is.

In the above operation, the average time for waiting for the rotation of the disk is T/2, where T is the rotation period.

In this way, the same data is written to the same location on each disk of the two disk devices, disk device A (5a) and disk device B (51+),
Even if one of the two disk devices (5a) and (5b) fails, the entire system is prevented from going down.

[Problems to be Solved by the Invention] Since the conventional magnetic disk system as described above is configured and operates as described above, even when reading data, an average time of T/2 is required for waiting for the rotation of the disk. There was a problem with that.

The present invention was made to solve this problem, and an object of the present invention is to provide a magnetic disk system that can shorten the average waiting time for disk rotation when reading data.

[Means for Solving the Problems] A magnetic disk system according to the first invention of this specification operates two disk devices at the same speed and sets the rotational phase difference to T/2 of the disk rotation period T. The magnetic disk system according to the second invention of this specification is designed to write the same data in the same sector of the same track of the two disk devices by synchronously driving the two disk devices so that The two disk drives are driven synchronously at the same speed and with a rotational phase difference of 0, and the same data is written in different sectors of the same track of the two disk drives at 180 degrees from each other.

In addition, as a conventional technique for accessing data with a phase difference of 180°, for example, Japanese Patent Application Laid-Open No. 1-134760
An invention that performs double writing on a single disk for the purpose of improving reliability, disclosed in the publication No. ``Optical Disc System'',
There are inventions such as those disclosed in Japanese Patent Application Laid-Open No. 63-66773 [Magnetic Head Machine for Magnetic Disk Devices], which write different data on a single disk for the purpose of shortening the access time for different data. The invention also does not allow for shortening the access time after double writing is performed on two disk devices in order to improve reliability.

[Operation] In this invention, the same data written on the same track of two disk devices has a time difference of T/2 of the rotation period T by the above-mentioned means, so that there is no need to wait for the rotation of the disk when reading data. It becomes possible to set the average time to T/4. [Example] An example of the present invention will be described below with reference to the drawings. 1 and 2 are diagrams each showing an embodiment of the magnetic disk system according to the first invention, FIG. 1 is a block diagram showing its configuration, and FIG. 2 is a time chart showing its operation, In each country, the same symbols as in FIG. 6 indicate the same or corresponding parts, (6) is the index pulse signal from the disk device A (5a), (7> is a delay circuit for delaying the index pulse signal (6), (8) is the output signal of delay circuit 1 (7).

The delay time of the delay circuit (7) is the rotation period of the disk 'F
The output signal (8) of the delay circuit (7) is set to 1/2 of
is the disk drive K which is the input signal to the delay circuit (7).
From the index pulse signal (6) of A (5a>)'I
” / 2. Then, the two disk drives (5a) and (5b) are rotated at the same speed, and the delay circuit (7) is installed in disk drive B (5b).
The output signal (8) of disk device A (5a) and disk device B (5b) is controlled by the rotation synchronization function of disk device B (5b) in synchronization with the output signal <8). They are driven synchronously so that the rotational phase difference is T/2. Therefore, the index pulse of the disk unit 17B (5b) becomes as shown in FIG. And two disk devices (5a). The same data is written in the same sector of the same track in (5b), but both disk devices (5a). The rotational phase difference between (5b) is T/2
Therefore, when reading data, the disk of one of the disk devices will reach the target sector during the maximum period of 1/2 rotation of the disk (T/2), and the average rotation when reading the disk waiting time T/4
It can be done.

The following FIGS. 3 to 5 are diagrams each showing an embodiment of the magnetic disk system according to the second invention, in which FIG. 3 is a block diagram showing its configuration, and FIG. 4 is a time chart showing its operation. Figure 5 shows two disk devices (5a), (
5b) is a diagram showing the arrangement of data on the track in FIG. In each country, the same symbols as in Figures 1, 2, and 6 indicate the same or equivalent parts, and (9) indicates the rotation synchronization signal. Disk device A (5a) and disk device B (5b) are synchronously driven by a rotation synchronization signal (9) at the same speed and with a rotational phase difference of O, and both disk devices (5a), ( 5b) index pulse is the fourth
As shown in the figure, they are the same.

Then, when a write request signal is issued from the CPU (2), the controller (4) completes the seek operation of each of the two disk devices, and then sends the request signal to the disk device (5).
Data is written to the track on the disk in a) at the sector position specified by the write request, and the disk device (
The track on the disk 5b) has a disk device (5a
), the same data is written to a different sector 180 degrees from the writing position.

That is, as shown in FIG. 5, for example, data "C" is written to sector 2 in disk device WA (5a), and written to sector 10 in disk device B (5b).

When waiting for the disk to rotate when reading data, disk device A (5a) waits for the sector specified in the write request to arrive, and disk device B
For (5b), 1 from the sector specified in the input request.
Wait for the arrival of a different sector at an 80° position. Therefore, at the longest, the disk of either disk device will reach the target sector during the time it takes for the disk to rotate 1/2 (T/2), and the average rotational waiting time when reading the disk will be T/4. It can be done.

In the above embodiment, the case where there is an even number (16) of sectors on one track is explained, but even if there is an odd number of sectors, it can be implemented in almost the same way by selecting different sectors at positions close to 180 degrees. can do.

[Effects of the Invention] As explained above, the present invention sets the rotational phase difference between both disk devices to 180 degrees, or sets the position of the sector where the same data is written between each disk of both disk devices to 180 degrees.
By making the difference by .degree., there is an effect that the average rotational waiting time when reading a disk can be halved compared to the conventional device.

[Brief explanation of drawings]

1 and 2 each show an embodiment of the first invention, FIGS. 3 to 5 each show an embodiment of the second invention, and FIG. 6 shows a conventional magnetic disk. FIG. 1 is a diagram showing a system. In the figure, (1) is the system bus, (2) is the CPU, (
3) is a memory, (4) is a controller, (5a) is a disk device A, (5b) is a disk device B, (6) is an index pulse signal, (7) is a delay circuit, (8) is a delay circuit &I( 7) is the output signal, and (9) is the rotation synchronization signal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a magnetic disk system that performs double writing of the same data on two disk devices each driven by a different drive device, the two disk devices are driven at the same speed and their rotational phase difference is A magnetic disk system comprising: means for synchronously driving the two disk devices so that the rotation period is 1/2; and means for writing the same data in the same sector of the same track of the two disk devices. (2) In a magnetic disk system that performs double writing of the same data on two disk devices each driven by a different drive device, the two disk devices are driven at the same speed and their rotational phase difference is zero. A magnetic disk system comprising: means for synchronously driving the two disk devices, and means for writing the same data in different sectors located at 180 degrees from each other on the same track of the two disk devices.